diff --git a/bin/install.js b/bin/install.js
index 8d37188..1f6957c 100755
--- a/bin/install.js
+++ b/bin/install.js
@@ -420,6 +420,15 @@ function captureSpawn(cmd, args) {
   catch (_) { return { status: 1, stdout: '', stderr: '' }; }
 }
 
+// spawnSync reports a missing binary as { status: null, error }, so the old
+// `(r.status || 0) === 0` checks read ENOENT as success — a machine without
+// the `claude` CLI got "installed: claude" with nothing installed and the
+// standalone-hook fallback skipped (issue #592). Every spawn result must pass
+// through here before being treated as "it worked".
+function spawnOk(r) {
+  return !!r && !r.error && r.status === 0;
+}
+
 function absoluteNodePath() {
   return process.execPath;
 }
@@ -444,10 +453,13 @@ async function installClaude(ctx) {
   } else {
     const r1 = runSpawn('claude', ['plugin', 'marketplace', 'add', REPO], null, opts.dryRun);
     const r2 = runSpawn('claude', ['plugin', 'install', 'caveman@caveman'], null, opts.dryRun);
-    if ((r1.status || 0) === 0 && (r2.status || 0) === 0) {
+    if (spawnOk(r1) && spawnOk(r2)) {
       results.installed.push('claude');
       pluginInstallSucceeded = true;
     } else {
+      if (r1.error || r2.error) {
+        warn('  claude CLI not found on PATH (or could not be spawned)');
+      }
       results.failed.push(['claude', 'claude plugin install failed']);
     }
   }
@@ -536,7 +548,7 @@ function installGemini(ctx) {
     }
   }
   const r = runSpawn('gemini', ['extensions', 'install', `https://github.com/${REPO}`], null, opts.dryRun);
-  if ((r.status || 0) === 0) results.installed.push('gemini');
+  if (spawnOk(r)) results.installed.push('gemini');
   else results.failed.push(['gemini', 'gemini extensions install failed']);
   process.stdout.write('\n');
 }
@@ -557,7 +569,7 @@ function installViaSkills(ctx, prov) {
   // documented form for "install every skill into a specific agent".
   const args = ['-y', 'skills', 'add', REPO, '--skill', '*', '-a', prov.profile, '--yes'];
   const r = runSpawn('npx', args, null, opts.dryRun);
-  if ((r.status || 0) === 0) results.installed.push(prov.id);
+  if (spawnOk(r)) results.installed.push(prov.id);
   else results.failed.push([prov.id, `npx skills add (${prov.profile}) failed`]);
   process.stdout.write('\n');
 }
@@ -1024,7 +1036,7 @@ function installMcpShrink(ctx) {
     ['mcp', 'add', 'caveman-shrink', '--', 'npx', '-y', MCP_SHRINK_PKG, ...upstream],
     null, opts.dryRun
   );
-  if ((r.status || 0) === 0) {
+  if (spawnOk(r)) {
     note(`    registered, wrapping: ${upstream.join(' ')}`);
     note(`    Edit ~/.claude.json mcpServers["caveman-shrink"] to change the upstream,`);
     note('    or `claude mcp remove caveman-shrink` to drop it.');
@@ -1043,7 +1055,7 @@ async function runInit(ctx) {
   if (opts.force)  args.push('--force');
   if (local && fs.existsSync(local)) {
     const r = runSpawn(absoluteNodePath(), [local, ...args], null, opts.dryRun);
-    return (r.status || 0) === 0;
+    return spawnOk(r);
   }
   // Curl-pipe fallback
   if (opts.dryRun) {
@@ -1055,7 +1067,7 @@ async function runInit(ctx) {
     await downloadTo(INIT_SCRIPT_URL, tmp);
     const r = child_process.spawnSync(absoluteNodePath(), [tmp, ...args], { stdio: 'inherit' });
     try { fs.unlinkSync(tmp); } catch (_) {}
-    return (r.status || 0) === 0;
+    return spawnOk(r);
   } catch (e) {
     warn('  ' + e.message);
     return false;
@@ -1159,7 +1171,7 @@ function uninstall(ctx) {
     const probe = captureSpawn('claude', ['plugin', 'list']);
     if (probe.status === 0 && /caveman/i.test(probe.stdout || '')) {
       const r = runSpawn('claude', ['plugin', 'uninstall', 'caveman@caveman'], null, opts.dryRun);
-      if ((r.status || 0) === 0) ok('  removed claude plugin');
+      if (spawnOk(r)) ok('  removed claude plugin');
     } else {
       note('  claude plugin not installed — skipping');
     }
@@ -1450,7 +1462,7 @@ async function main() {
     // --yes --all for the same reason as installViaSkills above (issue #370):
     // skip the interactive skill picker so curl|bash actually installs.
     const r = runSpawn('npx', ['-y', 'skills', 'add', REPO, '--yes', '--all'], null, opts.dryRun);
-    if ((r.status || 0) === 0) ctx.results.installed.push('skills-auto');
+    if (spawnOk(r)) ctx.results.installed.push('skills-auto');
     else ctx.results.failed.push(['skills-auto', 'npx skills add (auto) failed']);
     process.stdout.write('\n');
   }
diff --git a/tests/installer/e2e.freshinstall.test.mjs b/tests/installer/e2e.freshinstall.test.mjs
index d7b54e1..515c6b6 100644
--- a/tests/installer/e2e.freshinstall.test.mjs
+++ b/tests/installer/e2e.freshinstall.test.mjs
@@ -519,3 +519,38 @@ test('openclaw: append on a well-formed block stays a no-op', () => {
     fs.rmSync(dir, { recursive: true, force: true });
   }
 });
+
+// ── Test: missing `claude` CLI must be a FAILURE, not silent success (#592)
+// spawnSync reports ENOENT as { status: null, error }; the old
+// `(r.status || 0) === 0` coerced that to success, so the installer printed
+// "installed: claude", skipped the standalone-hook fallback, and left the
+// machine with nothing installed. Always runs: an empty PATH guarantees the
+// claude lookup fails even on machines that do have the CLI.
+test('missing claude CLI: reports failure and falls back to standalone hook wiring', () => {
+  const dir = freshTmpDir();
+  const emptyBin = path.join(dir, 'empty-bin');
+  fs.mkdirSync(emptyBin);
+  const configDir = path.join(dir, 'claude-config');
+  try {
+    // process.execPath instead of 'node': the stripped PATH must not break
+    // the test's own ability to launch the installer.
+    const r = spawnSync(process.execPath, [
+      INSTALLER, '--only', 'claude', '--skip-skills',
+      '--config-dir', configDir, '--non-interactive', '--no-mcp-shrink',
+    ], {
+      env: { ...process.env, PATH: emptyBin, CLAUDE_CONFIG_DIR: configDir, NO_COLOR: '1' },
+      encoding: 'utf8',
+    });
+    const out = (r.stdout || '') + (r.stderr || '');
+    assert.match(out, /plugin install did not succeed; falling back to standalone wiring/,
+      `fallback to standalone hooks did not trigger:\n${out}`);
+    assert.match(out, /claude plugin install failed/, 'claude was not reported as failed');
+    assert.ok(!/• claude\n/.test(out), 'claude must not be listed as installed');
+    assert.ok(fs.existsSync(path.join(configDir, 'hooks', 'caveman-activate.js')),
+      'standalone hooks were not written');
+    const settings = JSON.parse(fs.readFileSync(path.join(configDir, 'settings.json'), 'utf8'));
+    assert.ok(settings.hooks && settings.hooks.SessionStart, 'SessionStart hook not wired');
+  } finally {
+    fs.rmSync(dir, { recursive: true, force: true });
+  }
+});